1. Field
The present invention relates to medical devices and, in particular, to catheters that can easily be advanced into tortuous body lumens and for which the location of the catheters within body lumens can easily be verified.
2. Background Art
Medicine is providing ever-increasing demands for devices that can navigate narrow passageways to a desired location within a body so that diagnostic and therapeutic procedures can be performed at that location. Currently, elongated medical devices such as catheters can extend into a body from outside via an access point through various connected passageways to a target location.
One example of a tortuous pathway is the respiratory tract. The respiratory tract begins at the nose and mouth, which open to the trachea. The trachea travels downward into the chest at which it splits into the left and right main bronchi. The left and right main bronchi split at an angle from the trachea. The left main bronchus can be smaller in diameter than the right main bronchus and branches at a greater angle from the trachea than the angle at which the right main bronchus branches from the trachea. The main bronchi then split into lobar bronchi, which split into segmental bronchi. The segmental bronchi split into subsegmental bronchi.
Numerous procedures require intubation of the respiratory tract, including the left and right main bronchi, to aspirate mucus in the lungs or to delivery localized medicine, for example. Intubation of the left main bronchus from the trachea can be difficult because it may have a smaller diameter and greater angle relative to the trachea than the right main bronchus. For example, a typical procedure for aspirating fluid from the lungs can include introducing an endotracheal tube to the trachea of a patient, followed by extending a working catheter (e.g., an aspiration catheter) through a lumen of the endotracheal tube and into either the right or left main bronchus. Respiratory therapists seeking to intubate the left main bronchus with the aspiration catheter may mistakenly believe the left main bronchus has been intubated, when the catheter has actually entered the right main bronchus instead. In some instances, the endotracheal tube can be mistakenly inserted too deep so that its distal end extends into the right main bronchus, whereby the aspiration catheter can only access the right main bronchus. Often times, a specialist, such as a pulmonologist, is needed to insert a bronchoscope into the left main bronchus and aspirate the left main bronchus using the working channel of the bronchoscope. The bronchoscope is equipped with a vision system (including, for example, a fiberoptic system) and/or a fluoroscopic imaging system, to guide the bronchoscope into the left main bronchus. However, visualization equipment and the endoscopic procedure can be expensive, and specialists may not be readily available to conduct the procedure when desired.